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History of the Periodic Table: Difference between revisions
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== The Discovery of Element Periodicity == | == The Discovery of Element Periodicity == | ||
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Before the creation of the periodic table, the elements first had to be discovered. In 1869, 63 elements had been discovered. As the number of elements grew larger, scientists begin to see certain patterns in the elements. <ref>Western Oregon University. [https://www.wou.edu/las/physci/ch412/perhist.htm A BRIEF HISTORY OF THE DEVELOPMENT OF PERIODIC TABLE] ''wou''. Accessed May 21, 2017</ref> In 1829 Johann Dobereiner observed that there were groups of elements with properties that were similar. Chlorine, bromine, and iodine were some of the elements that he saw similarities in. These elements were gases, had a similar color, and other similar qualities. Dobereiner begin to construct triads with the elements, but these eventually fell through and did not all fit together. <ref name=BJU>Batdorf, Brad. [The Periodic Table, Chapter 5] '' | Before the creation of the periodic table, the elements first had to be discovered. In 1869, 63 elements had been discovered. As the number of elements grew larger, scientists begin to see certain patterns in the elements. <ref>Western Oregon University. [https://www.wou.edu/las/physci/ch412/perhist.htm A BRIEF HISTORY OF THE DEVELOPMENT OF PERIODIC TABLE] ''wou''. Accessed May 21, 2017</ref> In 1829 Johann Dobereiner observed that there were groups of elements with properties that were similar. Chlorine, bromine, and iodine were some of the elements that he saw similarities in. These elements were gases, had a similar color, and other similar qualities. Dobereiner begin to construct triads with the elements, but these eventually fell through and did not all fit together. <ref name=BJU>Batdorf, Brad. [The Periodic Table, Chapter 5] '' | ||
BJU Chemistry, Third Edition''. Published 2009.</ref> | BJU Chemistry, Third Edition''. Published 2009.</ref> Then in 1864 John Newlands thought that the elements may be able to be arranged according to atomic weight. He tried to arrange them in order of increasing atomic weight. This idea would not work because it groups elements together that have different chemical properties. But, he did make take steps in leading to the creation of the periodic table. Newlands was the first person to add atomic numbers to the elements, which is on the periodic table to this day. <ref>Purdue. [http://chemed.chem.purdue.edu/genchem/history/newlands.html John Newlands] ''Purdue edu''. Accessed May 21, 2017.</ref> | ||
Then in 1864 John Newlands thought that the elements may be able to be arranged according to atomic weight. He tried to arrange them in order of increasing atomic weight. This idea would not work because it groups elements together that have different chemical properties. But, he did make take steps in leading to the creation of the periodic table. Newlands was the first person to add atomic numbers to the elements, which is on the periodic table to this day. <ref>Purdue. [http://chemed.chem.purdue.edu/genchem/history/newlands.html John Newlands] ''Purdue edu''. Accessed May 21, 2017.</ref> | |||
== Mendeleev's Periodic Table == | == Mendeleev's Periodic Table == | ||
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Almost all of the credit for the periodic table goes to Dmitri Mendeleev. He arranged the elements by their atomic mass, like Newlands, but he did something different. He added in the elements that had not been discovered yet. He decided to do this because while he was studying the atomic masses he noticed that when they were put in order some of them increased more than others. <ref name=BJU/> He also arranged them vertically <ref>BBC. [http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/atomic_structure/periodictablerev1.shtml Atoms and the periodic table] ''BBC Science''. Accessed May 21, 2017.</ref>, and added the transition metals. He recognized that the transition metals did not fit into the chart so he separated them from the rest of the periodic table. Mendeleev summarized his work by writing the periodic law. The law states, "The properties of elements vary with their atomic masses in a periodic way". <ref name=BJU/> | Almost all of the credit for the periodic table goes to Dmitri Mendeleev. He arranged the elements by their atomic mass, like Newlands, but he did something different. He added in the elements that had not been discovered yet. He decided to do this because while he was studying the atomic masses he noticed that when they were put in order some of them increased more than others. <ref name=BJU/> He also arranged them vertically <ref>BBC. [http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/atomic_structure/periodictablerev1.shtml Atoms and the periodic table] ''BBC Science''. Accessed May 21, 2017.</ref>, and added the transition metals. He recognized that the transition metals did not fit into the chart so he separated them from the rest of the periodic table. Mendeleev summarized his work by writing the periodic law. The law states, "The properties of elements vary with their atomic masses in a periodic way". <ref name=BJU/> | ||
== The Modern Periodic Table == | |||
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Although Mendeleev's periodic table was brilliant, there were still some things wrong about it. The way that the elements were arranged still did not always group the elements that were similar. One of Ernst Rutherford's assistants, Henry Moseley, suggested that they develop a way to count the number of protons in an atom's nucleus. Once he created a way to do this, he realized they needed to revise the periodic table to make it more accurate, now that they could find the number of protons in an atom. He changed the periodic table and the periodic law. The modern periodic law states, "The properties of elements vary with their atomic numbers in a periodic way". <ref name=BJU/> | Although Mendeleev's periodic table was brilliant, there were still some things wrong about it. The way that the elements were arranged still did not always group the elements that were similar. One of Ernst Rutherford's assistants, Henry Moseley, suggested that they develop a way to count the number of protons in an atom's nucleus. Once he created a way to do this, he realized they needed to revise the periodic table to make it more accurate, now that they could find the number of protons in an atom. He changed the periodic table and the periodic law. The modern periodic law states, "The properties of elements vary with their atomic numbers in a periodic way". <ref name=BJU/> | ||
The modern periodic table has more than the 63 elements that were discovered by Mendeleev. Most of the periodic tables up to this date have up to 109 elements. It has 18 groups in vertical columns. The vertical columns are labeled by roman numerals or numbers, and each horizontal row is called a period, and the periodic table consists of seven periods. <ref>GENESIS. [https://genesismission.jpl.nasa.gov/educate/scimodule/cosmic/explore_2ST.pdf Cosmic Chemistry: An Elemental Question] ''Genesis Education''. Accessed May 21, 2017.</ref> | The modern periodic table has more than the 63 elements that were discovered by Mendeleev. Most of the periodic tables up to this date have up to 109 elements. It has 18 groups in vertical columns. The vertical columns are labeled by roman numerals or numbers, and each horizontal row is called a period, and the periodic table consists of seven periods. <ref>GENESIS. [https://genesismission.jpl.nasa.gov/educate/scimodule/cosmic/explore_2ST.pdf Cosmic Chemistry: An Elemental Question] ''Genesis Education''. Accessed May 21, 2017.</ref> | ||
==References== | ==References== | ||
